FIG. 9 shows an electric connection box as a resin molded article 100, in which electric components, such as a terminal and a bus bar, are contained. The resin molded article 100 as the electric connection box includes a main body 110 for containing the electric components, and joint sections 120 for attaching the main body 110 to a mating member, such as an actuator.
Two joint sections 120 are formed to be spaced apart each other on the outer wall surface 115 of the main body 110. Each of the joint sections 120 is integrally formed with the main body 110 to protrude from the outer wall surface 115 on an upper side of the main body 120. The joint section 120 is attached to the mating member by inserting a joint member, such as a screw, into and through the joint section and screwedly fastening the joint member extended therethrough to the mating member. Therefore, the joint section 120 has a cylindrical section 121 extending in a direction extending through a paper surface and adapted to allow the joint member to be inserted therein and therethrough. A collar (bushing) is insert-molded in the cylindrical section 121.
As shown in FIG. 10, a pair of inclined wall sections 123 for providing strength to the cylindrical section 121 are obliquely and integrally extended from the left and right sides of the cylindrical section 121, and an extended end portion of each of the inclined wall sections 123 is provided to be connected to the outer wall surface 115 of the main body 110. The inclined wall sections 123 on both the left and right sides of the cylindrical section 121 integrally extend over an equal length, and thus the entire of the joint section 120 form a triangle (equilateral triangle), thereby achieving lightweighting and compacting thereof. The left and right inclined wall sections 123 are formed to have an equal thickness. In addition, bored sections 125 are respectively formed between each of the inclined wall sections 123 and the outer wall surface 115 of the main body 110, and thus deforming prevention and the like upon molding is achieved.
FIG. 11A is a sectional view taken along a line A-A in FIG. 10 and FIG. 11B is a sectional view taken along a line B-B in FIG. 10. As shown in FIGS. 11A and 11B, bottom wall sections 127 are respectively formed on a longitudinal end portion of each of the bored sections 125 to connect the outer wall surface 115 of the main body 110 with the inclined wall sections 123. A thickness of each of the bottom wall sections 127, similarly to the inclined wall sections 123, is formed to be equal to each other.
The thicknesses of the left and right inclined wall sections 123 and the thicknesses of the bottom wall sections 127 continued from the left and right inclined wall sections 123 are equal. Thus, since the thicknesses of the inclined wall sections 123 and the bottom wall sections 127 are formed to be equal, the joint section 120 becomes into a left-right symmetric shape.
The resin molded article 100 as described above is formed by injection molding of a resin, and reference numeral 140 in FIG. 9 designates a location of a gate for injecting the resin into a mold. By being injected from the gate 140, the resin flows through inside the mold, and thus the main body 110 and the joint section 120 are molded.
FIG. 12 shows resin flows for forming the joint section 120. As shown in an arrow, the resin upwardly flow at an equal flow rate through the left and right inclined wall sections 123 and then flows of the resin meet at the apex of the triangle at which the left and right inclined wall sections 123 are coupled to each other. FIG. 13 shows a top surface of the joint section 120. In FIGS. 12 and 13, reference numeral 150 designates a welded portion at which flows of the resin meet, and the welded portion 150 is formed at the apex (i.e., a leading end central portion of the cylindrical section 121) of the triangle.
Meanwhile, as patent documents related to the resin molded article 100 as described above, the following Patent Documents 1 to 5 can be cited.